The present invention relates generally to heating, ventilation and air conditioning (HVAC) systems for vehicles, and more particularly to HVAC systems employed with hybrid vehicles having belt driven refrigerant compressors.
On vehicles that employ internal combustion engines, some hybrid versions shut off the engine while stopped at a traffic light in order to improve fuel economy. For such vehicles that also employ a belt driven refrigerant compressor (i.e., the belt driven by the engine), the compressor cannot operate while the engine is off. So, while a vehicle is waiting at a stop light on a hot day, the requirement to keep passengers thermally comfortable is in direct conflict with increasing fuel economy.
Some have addressed this concern by using an electric driven compressor, which can operate with the engine off. However, the electric compressor operates at a higher cost in energy and materials due to the complexity and additional stages in power transfer. This higher cost may be unacceptable for certain vehicles.